CHEMICAL AGENT DETECTOR WITH 30 SECOND CYCLE
A gas chromatography instrument is provided that is capable of analyzing samples both quickly and accurately. The detector includes a first unit and a second unit that alternate between collection mode and desorption mode. This allows one unit to collect the sample, while the other unit desorbs another sample before the units switch operations. The alternating collection and desorption modes allows the detector to generate a data point approximately every thirty seconds, with each alternating unit.
This Application claims priority to U.S. Provisional Patent Application Ser. No. 62/915,835, filed on Oct. 16, 2019, entitled “Chemical Agent Detector with 30 Second Cycle,” currently pending, the entire disclosure of which is incorporated herein by reference.
FIELD OF INVENTIONThe present invention relates generally to air sampling devices or detectors used for gathering and analyzing trace elements from a particular environment such as a suspected contaminated area and, more particularly, to a gas chromatograph instrument capable of collecting air samples, desorbing the sample onto a gas chromatograph column to separate components, detecting the chemical(s) using a detector, and reporting the results every thirty seconds.
BACKGROUND OF INVENTIONThere are many applications in which it is desirable to collect and capture air samples from an environment suspected of contamination. Examples include collecting air samples in potential hazardous chemical release situations, collecting vapor samples from bulk chemical storage locations, and the like. Many different types of sampling devices and detectors exist today for capturing samples of trace elements or contaminants from a particular environment. Once collected, such samples are analyzed to determine the nature of the chemicals involved, the level of contamination in the air, and the degree of risk personnel may be exposed to in the contaminated area.
One method of analyzing collected air samples is through gas-liquid chromatography, commonly referred to as gas chromatography. Gas chromatography is a process used for analyzing a complex sample by separating the analytes within the sample to determine the identity of the analytes in the sample. Other information about the analytes, such as the concentration of each analyte within the sample, may also be obtained. A gas chromatograph is used for separating the sample by injecting the sample onto a column through which the sample passes.
The column temperature, column length, vapor pressure, polarity of components compared to the polarity of the stationary phase on the column, carrier gas flow rate, and amount of material injected determines the time of retention and the quality of separation. Thus, the time for a sample to be analyzed and the accuracy of the analyzation are dependent on each other. Generally, a high column temperature results in a short retention time but also a poor separation. However, users may need a sample analyzed both quickly and accurately, such as when process monitoring or for air safety monitoring.
It is therefore desirable to provide a gas chromatography instrument capable of analyzing samples both quickly and accurately.
SUMMARY OF INVENTIONThe present invention overcomes many of the shortcomings and limitations of the prior art devices discussed above. The invention described includes several embodiments of air sampling devices used for gas chromatography, and it is capable of reporting the results every thirty seconds.
In one embodiment, the detector includes a first unit and a second unit. The first unit and the second unit work in conjunction with each other, such that the first unit may be in a collection mode while the second unit is in a desorption mode. In collection mode, a sample moves through a heated sample line until the sample reaches a pre-concentrator tube. In a preferred embodiment, the pre-concentrator tube is a curved cylinder, with a C-like shape and is made out of metal or a metal-like material. This pre-concentrator tube may contain a two (2) cm bed-depth of a collection sorbent which is specific for the material being collected.
The first unit then switches from collection mode to its desorption mode, while the second unit switches from the desorption mode to the collection mode. When the first unit is in its desorption mode, the carrier gas flows through the sorbent contained in the pre-concentrator tube. A current runs through the metal or metal-like pre-concentrator tube to assist in heating the pre-concentrator tube (as well as the solvents and sample within the pre-concentrator tube). Once the sample within the pre-concentrator tube is heated, the sample is desorbed. The desorbed sample flows to the main column, which separates any compounds or interferences, thus creating a response through at least one flame photometric detector.
Thus, the first unit and second unit alternate between collection mode and desorption mode, allowing one unit to collect the sample, while the other unit desorbs another sample. The units can then switch. The alternating collection and desorption modes allow the pre-concentrator tube to heat and cool within approximately thirty seconds. The detector is therefore able to generate a data point approximately every thirty seconds, with each alternating unit.
These and other aspects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed description in connection with the accompanying drawings.
The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.
Turning to
As illustrated in
The stationary body section of the switching valve 25 further includes a series of ports, including a first port 30. In one embodiment, the switching valve 25 may include six ports (30, 35, 70, 75, 80, 85). The switching valve 25 may include more or fewer ports 30 in alternative embodiments. Each port 30 extends through the stationary body section, from a stationary body sidewall, though the stationary body section, and to the cavity, adjacent to the rotating valve core. The rotating valve core includes at least one groove allowing at least two ports to be in fluid communication with each other.
In one embodiment, when either unit 10, 15 is in collection mode, a sample can be drawn in through an inlet associated with a first port 35 of the six ports within the switching valve 25. The sample can then move from the first port 35 to the sixth port 40, where it exits the switching valve 25. The sample then moves through a heated sample line 45 until the sample reaches a pre-concentrator tube 50.
In a preferred embodiment, the pre-concentrator tube 50 is a curved cylinder, as shown in
In one embodiment, the length of the pre-concentrator tube 50 may range from 4.9 to 5 inches, with a 0.0625 inch outer diameter and a 0.040 inch inner diameter. The pre-concentrator tube 50 may have other lengths and diameter in alternative embodiments. The design and materials of the pre-concentrator tube 50 allow for fast heating and cooling (e.g., in less than 30 seconds). Heating may occur with heating elements, or by running an electrical current directly through the metal of the pre-concentrator tube 50, or via other known techniques. Cooling may occur by blowing ambient air across the pre-concentrator tube 50, or by other known techniques.
Turning back to
As the sample flows into either unit 10, 15 from the first port 35 to the pre-concentrator tube 50, carrier gas is supplied from a vessel (not shown) and enters the unit 10 through a fourth port 80 before exiting the switching valve 25 through the fifth port 85. A non-inclusive list of possible carrier gasses includes helium, nitrogen, and hydrogen. The carrier gas continues to flow from a fifth port valve 85 into a main column 90. In this orientation, the carrier gas may help to cleanse the main column 90.
When a unit 10, 15 switches from the collection mode to a desorption mode, as illustrated in
As the rotating valve core is switched to the second position to put a unit 10, 15 in to desorption mode, a current is run through the metal or metal-like pre-concentrator tube 50 to assist in quickly heating the pre-concentrator tube 50 (as well as the solvents and collected chemical sample within the pre-concentrator tube 50). As the sample within the pre-concentrator tube 50 is heated, the sample is desorbed. The sample is pushed from the pre-concentrator tube 50 by carrier gas flow from a pressurized gas cylinder (not illustrated), and re-enters the port switch valve 25 through the sixth port valve 40. The sample then exits the port switch valve 25 through the fifth port valve 85 before flowing to the main column 90. The main column 85 separates compounds or interferences creating a response through at least one flame photometric detector 95. The device can further measure a mass per unit volume for the desired output of the instrument.
For example, while the unit 10 is in its desorption mode as shown in
Thus, unit 10 and unit 15 alternate between collection mode and desorption mode, allowing one unit to collect the sample, while the other unit desorbs the sample. The alternating collection and desorption modes allow the pre-concentrator tube 50 to heat and cool within approximately thirty seconds. The device 5 is therefore able to generate a data point approximately every thirty seconds, with each alternating unit 10 or 15 generating a data point approximately every minute.
Additional features of the device 5 may include each unit 10 and 15 of the detector being further able to sample or take in the sample at the desired interval of time within the thirty second window. For example, the units 10 and 15 may be designed or programmed to sample at ten seconds, at twenty seconds, or at thirty seconds within the thirty second window.
In one embodiment, an injection port 100 may be positioned between the sixth port 40 and the pre-concentrator tube 50 in the pre-concentrator line 45. Thus, when a unit 10, 15 is in desorption mode, a sample can be directly injected into the sixth port 40. The sample would then exit through the fifth port 85 and proceed directly to the main column 90. This allows direct testing of the main column 90 and flame photometric detector 95. In such a test, no sample is collected by the pre-concentrator tube 50 immediately preceding the desorption mode test.
Alternatively, or in addition once the main column 90 and flame photometric detector 95 have been tested, the sample injection port 100 can be used to test the collection capabilities of the pre-concentrator tube 50 when the unit 10, 15 is in collection mode. A known sample can be injected at the injection port 100, where it flows directly to the pre-concentrator tube 50. The system can then switch to the desorption mode, where the collected sample is run through the main column 90 and flame photometric detector 95. The collection abilities of the pre-concentrator tube 50 can be determined, due to the known characteristics of the direct-injected sample.
In yet another embodiment, illustrated in
However, when the second unit 15 switches to desorption mode, in addition to the above-discussed switches of its six-port valve 25B, the four port valve 105 switches so that the first port 125 is connected with the fourth port 115, and that the sample from the second unit 15 is fed to the single flame photometric detector 95. The third port 110 of the fourth port 105 is then connected with the second port 130, such that the sample-less carrier flow of the first unit 10 is vented.
As is evident from the foregoing description, certain aspects of the present invention is not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications, applications, variations, or equivalents thereof, will occur to those skilled in the art. Many such changes, modifications, variations and other uses and applications of the present constructions will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. All such changes, modifications, variations and other uses in applications which do not depart from the spirit and scope of the present inventions are deemed to be covered by the inventions which are limited only by the claims which follow.
Claims
1. An air sampling device comprising:
- a first unit and a second unit each comprising at least a respective one of the following: a port switch valve; a sample inlet in fluid communication with a first port of the port switch valve; a curved pre-concentrator tube formed from a material capable of conducting electricity, a first end of the pre-concentrator tube in fluid communication with a sixth port of the port switch valve, and a second end of the pre-concentrator tube in fluid communication with a third port of the port switch valve; an exhaust line in fluid communication with a second port of the port switch valve; a carrier inlet in fluid communication with a fourth port of the port switch valve; a main column in fluid communication with a fifth port of the port switch valve; and a flame photometric detector in fluid communication with the main column;
- wherein the first unit and the second unit each have a first and second configuration;
- wherein the first unit is in the first configuration when the second unit is in the second configuration, and vice versa;
- wherein in the first configuration, the first port is in fluid communication with the sixth port, the second port is in fluid communication with the third port, and the fourth port is in fluid communication with the fifth port;
- wherein in the second configuration, the first port is in fluid communication with the second port, the third port is in fluid communication with the fourth port, and the fifth port is in fluid communication with the sixth port;
- wherein the first unit and the second unit each being capable of alternating between a collection mode in the first configuration and desorption mode in the second configuration, the first and second unit each completing one cycle ever sixty seconds or less such that one of the first unit and second unit generates a data point every thirty seconds or less.
2. The air sampling device of claim 1, wherein the port switch valve of the first unit includes a plurality of ports.
3. The air sampling device of claim 1, wherein the port switch valve of the second unit includes a plurality of ports.
4. The air sampling device of claim 2, wherein when the first unit is in the collection mode, the plurality of ports are in a first configuration, and wherein when the first unit is in the desorption mode, the plurality of ports are in a second configuration.
5. The air sampling device of claim 3, wherein when the second unit is in the collection mode, the plurality of ports are in a first configuration, and wherein when second first unit is in the desorption mode, the plurality of ports are in a second configuration.
6. The air sampling device of claim 1, wherein the first and second units are located within a single housing.
7. The air sampling device of claim 2, wherein when the first unit is in the collection mode, a carrier gas may be provided to the main column via two or more of the plurality of ports.
8. The air sampling device of claim 3, wherein when the second unit is in the collection mode, a carrier gas may be provided to the main column via two or more of the plurality of ports.
9. The air sampling device of claim 1, wherein when the first unit is in the desorption mode, sample provided in the pre-concentrator tube is heated.
10. The air sampling device of claim 1, wherein when the first unit is in the desorption mode, sample provided in the pre-concentrator tube is heated.
11. An air sampling device comprising:
- a first unit and a second unit,
- the first unit and the second unit each being capable of alternating between a collection mode and desorption mode, each unit being in an opposite mode from the other, and the first and second unit working in conjunction with each other so that the device generates a data point in thirty seconds or less.
12. The air sampling device of claim 11, wherein the first unit comprises: the second unit comprises:
- a port switch valve;
- a curved pre-concentrator tube formed from a material capable of conducting electricity;
- a main column; and
- a flame photometric detector; and
- a port switch valve;
- a curved pre-concentrator tube formed from a material capable of conducting electricity;
- a main column; and
- a flame photometric detector.
13. The air sampling device of claim 12, wherein the port switch valve of the first unit includes a plurality of ports.
14. The air sampling device of claim 12, wherein the port switch valve of the second unit includes a plurality of ports.
15. The air sampling device of claim 13, wherein when the first unit is in the collection mode, the plurality of ports are in a first configuration, and wherein when the first unit is in the desorption mode, the plurality of ports are in a second configuration.
16. The air sampling device of claim 14, wherein when the second unit is in the collection mode, the plurality of ports are in a first configuration, and wherein when second first unit is in the desorption mode, the plurality of ports are in a second configuration.
17. The air sampling device of claim 13, wherein when the first unit is in the collection mode, a carrier gas may be provided to the main column via two or more of the plurality of ports.
18. The air sampling device of claim 14, wherein when the second unit is in the collection mode, a carrier gas may be provided to the main column via two or more of the plurality of ports.
19. The air sampling device of claim 12, wherein when the first unit is in the desorption mode, sample provided in the pre-concentrator tube is heated.
20. The air sampling device of claim 12, wherein when the first unit is in the desorption mode, sample provided in the pre-concentrator tube is heated.
Type: Application
Filed: Oct 16, 2020
Publication Date: Apr 22, 2021
Inventors: Eric Peters (Prairie Village, KS), Louis Anderson (Bel Air, MD), Charmel Grisham (Grain Valley, MO), Sara Paalhar (Liberty, MO), Sylvanna Couch (Lenexa, KS)
Application Number: 17/072,714